Tanacetum parthenium L. Schulz-Bip. (syn. Chrysanthemum parthenium, Leicanthemum parthenium, Matricaria parthenium, Pyrethrum parthenium) is a plant belonging to the Compositae (Asteraceae, Matricaria or daisy) family. Tanacetum parthenium is known under following common names: altamisa, amargosa, bachelor's buttons, featherfew, featherfoil, febrifuge plant, feverfew, flirtwort, grande camomille, manzanilla, matricaria, midsummer daisy, moederkruid, Santa Maria, and varadika. Of these common names, the name “feverfew” is used most frequently.
Feverfew is a short perennial plant that grows 15-80 cm tall. The stems stand straight up and are furrowed and hairy. The leaves are double divided feathery green leaves having serrate margins. The flower has white ray petals and a yellow center that is flat. The odor of the plant when bruised is strong, aromatic, and bitter. Feverfew has been grown for at least 2000 years and it is a native of the Balkan Peninsula and the Caucasus mountains. Presently, feverfew grows in Europe, North America, South America, North Africa, China, Japan, and Australia. The optimal conditions for feverfew cultivation are: well-drained soil having pH=6.0 . . . 6.7 (optimum pH=6.3); full sun or partial shade; suited to hardiness in USDA temperature zones from nine to five without protection. The best climate for feverfew is zones five and seven. With protection feverfew can be cultivated in zones three and four, although in a continental climate (e.g., Kansas, USA; Saskatchewan, Canada) feverfew sometimes is considered an annual plant.
Ancient Greeks and early Europeans used feverfew to treat fever, inflammation, and swellings, as well as to repel insects and to treat bites and stings. Within the past 20 years, feverfew has attracted considerable interest for the treatment of migraines, arthritis, and inflammatory diseases. The parts of the plant which are utilized are dried or fresh leaves and flowering aerial parts. Feverfew is used in the form of a crude herb, dried powder, fresh leaf, freeze-dried leaf capsule, dried leaf capsule, softgel capsule, tincture, infusion (e.g., tea), extracts, and ingredients of functional drinks. Apparently, the feverfew whole plant acts in a fashion similar to nonsteroidal anti-inflammatory agents. However, feverfew extracts act rather similar to cortisone (see, e.g., Feverfew. Botanical Monograph, American Journal of Natural Medicine 4(6):28-29 (1997)).
Such discrepancy and broad-spectrum activities attract attention to and the investigation of active ingredients in the plant and its derivatives. The major known active chemicals in feverfew are sesquiterpene lactones (total content ≦1.8%) and essential oils (total content ≦0.07%). The list of feverfew active compounds include the following: (i) sesquiterpene lactones (including artecanin, canin, 10-epi-canin, chrysanthemolide, chrysanthemonin, epoxyartemorin, 1β-hydroxyarbusculin, 3β-hydroxyparthenolide, 8β-hydroxyreynosin, magnoliolide, parthenolide, reynosin, santamarin, seco-tanaparthenolide A, tanaparthin, tanaphthin-1α,4α-epoxide, tanaparthin-1β,4β-epoxide); (ii) sesquiterpenes (including camphor, β-farnesene, and germacrene); (iii) monoterpenes; (iv) flavonols (including tanetin, kaempherols, quercetagetins, apigenin, luteolin, and chrysoeritol); and (v) spiroketal enol ether polyines.
The most abundant group of these compounds is a group of α-unsaturated γ-lactones; particularly, parthenolide, which represents ˜85% of α-unsaturated γ-lactones. Parthenolide, which is apparently located in oil cells on feverfew leaf surface is the most well-known and well-studied (see, e.g., Smith et al., J. Chromatogr., 627:255 (1992); and Smith, R. M., LC GC Int., (Jan. 8-15, 1996)). The α-unsaturated γ-lactones, including parthenolide, are considered to be the fundamental ingredients responsible for the biological activities of feverfew, but are also the same ingredients often responsible for allergic reactions caused by feverfew derivatives.
For example, feverfew preparations used in successful clinical trials had a parthenolide content of 0.4% to 0.66%, which exceeds the concentrations capable of initiating ulceration, exudative dermatitis, and pathological effects arising from external contact (see, e.g., Awang, D. V. C., “Feverfew,” Can. Pharm. J., 122:266-270 (1989)). At the same time, about 10-18% of feverfew users have reported some usually mild and reversible adverse effects (see, e.g., Ernst et al., “The efficacy and safety of feverfew (Tanacetum parthenium L.): an update of a systematic review,” Public Health Nutrition, 3(4a):509-514 (2000); Porter et al., “Feverfew in Saskatchewan,” (www.agr.gov.sk.ca/DOCS/crops/special_crops/feverfew.asp?firstPick=&secondpck=&third pick=Production%20Information) (2004)) and parthenolide could be responsible for these adverse effects. The ability of α-unsaturated γ-lactones (including parthenolide) to trigger many allergic reactions is well documented (see, e.g., Arch. Dermatol. Forsch, 251(3):235-244 (1975); Arch. Dermatol. Forsch, 255(2):111-121 (1976); Contact Dermatitis, 38(4):207-208 (1988); Am. J. Contact Dermatol., 1:49-50 (1998-1999); Br. J. Dermatol, 132(4)543-547 (1995)).
In recent years, efforts have been directed toward preparation of feverfew extracts, which purport to be substantially-free from α-unsaturated γ-lactones and, more particularly, substantially-free from parthenolide (see, e.g., U.S. Pat. No. 6,224,875 and U.S. Pat. No. 6,479,080). It should be noted that “substantially-free from α-unsaturated γ-lactones” and “substantially-free from parthenolide” mean an extract having a weight content of α-unsaturated γ-lactone or parthenolide, respectively, below about 0.1%, more preferably below 0.1%, more preferably below about 0.09%, and most preferably below 0.07%. Because the above contents are lower than that in an average feverfew phytomass having from 0.4 to 1.8% of parthenolide (see, e.g., Marino L., “The effect of clonal micropropagation on parthenolide content in two genotypes of feverfew, Tanacetum parthenium,” AgroFarm Technologies Feverfew Report, London, Ontario (2004)), many steps of complex extraction using several organic solvents and purification, including complete evaporation of solvents and utilization of ion-exchange resin, are required to produce extracts having decreased content of α-unsaturated γ-lactones and particularly parthenolide.
The organic solvent extracts mentioned above are obtained from dried feverfew phytomass utilizing a process comprising the following steps: (a) extracting a quantity of plant material from the aerial portion of the plant with acetone, alcohols or a mixture of these solvents with water; (b) extracting the material from step (a) with a hydrocarbon solvent; (c) extracting the remaining non-hydrocarbon phase with a non-polar solvent; (d) evaporating the non-polar solvent extract and redissolving the residue in water-alcoholic solution, and then treating the redissolved residue with a strong basic resin; (e) eluting the resin with an alcohol and removing the eluted solution; (f) treating the resin with an alcoholic or water-alcoholic solution of an acid, concentrating the solution and extracting the resulting residue with a non-polar solvent; (g) evaporating the non-polar solvent from step (f) to form a residue which is added to the residue from the evaporation of the hydrocarbon extract from step (b) and to the acetonic or alcoholic phase obtained after the extraction with the non-polar solvent of step (c); and (h) evaporating the solvent and drying the remaining residue.
The preferred solvents for the various extraction steps include, but are not limited to, the following: for Step (a): acetone, methanol, ethanol or mixtures thereof with water; for Step (b): hexane, n-pentane, petroleum ether, ligroin; for Step (c): methylene chloride, chloroform, ethyl acetate, preferably methylene chloride; and for Step (f): ethyl acetate.
According to the U.S. Pat. Nos. 6,224,875 and 6,479,080, this “substantially free from parthenolide” extract has favorable pharmacological properties together with reduced risk of inducing allergic reactions. However, the above extract is isolated with sequential processing using organic solvents, which belong to four different groups, and which may have limited compatibility with many conventional components of skin care formulations. Therefore, the applicability of the above extract as an ingredient for skin care products has certain limits (e.g., not readily soluble in water).
Although the described feverfew extract is “substantially free from parthenolide,” it is not truly parthenolide free material due to the allowed residual parthenolide content. Well-known high specific activities of parthenolide itself can contribute to both pharmacological properties and residual allergenicity of the extract, especially when used at high concentrations. It is important that pharmacological properties of the above extract be limited by activities of only those feverfew ingredients which are solubilized in certain solvents at certain conditions. Therefore, such extract represents only part of the active components existing in living feverfew plants. For example, freeze-dried feverfew leaves and dried leaves demonstrated significant beneficial effect when compared to a placebo, but ethanol extracts of feverfew were ineffective (see, e.g., Ernst et al., “The efficacy and safety of feverfew (Tanacetum parthenium L.): An update of a systematic review,” Public Health Nutrition, 3(4a):509-514 (2000)).
With respect to comparison of specific activities found in different forms of feverfew products, it should be noted that preparation of whole dried leaves has been proven to be more effective than its extracts, and, additionally, extracts of dried and fresh feverfew have marked differences in the pharmacological potency and profiles (see, e.g., Barsby et al., “Feverfew and vascular smooth muscle: Extracts from fresh and dried plants show opposing pharmacological profiles, dependent upon sesquiterpene lactone content,” Planta Medica, 59:20-25 (1993)). Thus, relative and in contrast to dried feverfew leaf extracts, the fresh leaf extracts have: (a) reduced inactivating voltage-dependent potassium current in a concentration-related manner; (b) dose-dependent inhibition of leukocyte production of tromboxane B2 and leukotriene B4; and (c) inhibited muscle response to triptamine, tromboxane, and reduced acetylcholine induced relaxation.
Interestingly, the strong desire to maximize the efficacy of feverfew products led recently to increased production of products containing all plant components which would be minimally impacted by the processing of the plant. Among these products are preparations of freeze-dried feverfew leaves, although such material is suitable for limited applications, and skin care is not among them.
Additionally, activities of feverfew extracts and the level of parthenolide in these extracts depend on choice of solvent(s) end explored extraction method (see, e.g., Kaplan, M., “Comparison of Supercritical Fluid and Solvent Extraction of Feverfew (Tanacetum parthenium),” Turk J. Chem, 26:473-480 (2002)). Thus, material extracted by solvent extraction and supercritical fluid extraction differ. For example, supercritical fluid CO2 extracts have greater parthenolide content than chloroform extracts, and more in acetone extracts thereafter.
Composition of feverfew varies significantly, depending on the source of plant material and cultivation and harvesting conditions. Enormous variations in the amount of parthenolide have been found. For example, American-grown plants contain ≦50% of the concentration of parthenolide found in British and French-grown feverfew. Parthenolide contents were higher for dry land compared to irrigated feverfew. It was found that subjecting feverfew to a single water stress event can increase parthenolide content (Fonseca et al., “Parthenolide and abscisic acid synthesis in feverfew are associated but environmental factors affect them dissimilarly,” J. Plant Physiology, 162:485-494 (2005)). Flowers contained the highest levels of parthenolide, while stems contained the least parthenolide. The parthenolide content in flowers increased and the content of the stems and leaves decreased as harvest was delayed. Feverfew harvested during the afternoon contained significantly more parthenolide than plants harvested in the morning and exposure of feverfew to ultraviolet (UV) light resulted in significantly decreased parthenolide content. It should be noted that wide variation in amount of parthenolide in feverfew derivatives could be the essential result of interaction of two major factors: cultivation conditions and processing methods. Unfortunately, U.S. Pat. Nos. 6,224,875 and 6,479,080 do not provide any information relating to reproducibility of the “substantially free from parthenolide” feverfew extract. However, as described above, large variability of raw material may have significant impact on extract properties.
Thus, there are many genetic, geographic, climatic, and technological factors, which lead to poor reproducibility and less than fully optimal quality of conventional feverfew products and extracts (see, e.g., Hepinstall et al., “Parthenolide content and bioactivity of feverfew (Tanacetum parthenium (L.) Schultz-Bip.). Estimation of commercial and authenticated feverfew products,” J. Pharm. Pharmacol., 44:391-395 (1992); Draves, A. H. and S. E. Walker, “Parthenolide Content of Canadian Commerical Feverfew Preparations Label Claims are Misleading in Most Cases,” Canadian Pharm J, 136(10):23-30 (December 2003/January 2004)) and these factors create serious problems for broad utilization of feverfew derivatives in herbal medicine and skin care.
Therefore, there is a need for a method of production of highly reproducible and parthenolide free feverfew derivatives having a broad spectrum of desirable biological activities, which are not limited by only those activities which have affinity to certain solvents, i.e., which are not otherwise subject to the limitations of conventional chemical extraction.